The following is a tabulation of some prior art that presently appears relevant:
U.S. PatentsPat. No. Kind CodeIssue DatePatentee5,800,825ASep. 1, 1998McMullen8,236,063B2Aug. 7, 2012Reichert et al.U.S. Patent Application Publications
None Found
Foreign Patent Document
None found
Nonpatent Literature Documents
None found